Textile bleaching process



FIP8309 3,397,033 TEXTILE BLEACHING PROCESS Peter Ney, Frankfurt amMain, and Walter Kuhnmiincll, Frankfurtlam Main-Heddernheim, Germany,assignors to Deutsc'he Goldund Silber-Scheideanstalt vormals Roessler,Frankfurt am Main, Germany No Drawing. Filed Apr. 5, 1965, Ser. No.445,696 Claims priority, application Germany, Apr. 9, 1964,

,1 3 Claims. (Cl. 8-111) ABSTRACT OF THE DISCLOSURE The presentinvention relates to an improved process for bleachingfibers,especially, cellulosic fibers, either as such or in the form of yarns,woven fabrics or knit goods, in which the goods to be bleached areimpregnated with an aqueous bleaching solution, the excess bleachingsolution is removed by squeezing or centrifug" ing and the goods arethen subjected to a heat treatment followed by washing which simplifiesand reduces the time required for the bleaching.

In the bleaching of textile goods, processes are known in which thegoods are first impregnated with the bleach ing solution at roomtemperature or raised temperatures, the excess bleaching solution thensqueezed out or spun out, and then heated, for example, by a steam jetand then held at an elevated temperature for a longer period of time.This procedure in general provides good bleaching results. However, itrequires a considerable period of time and considerable energy in orderto provide the necessary elevated temperature over the longer periods oftime required.

In the further development of this process, it Was found to be expedientin some instances to store the goods which had been impregnated with thebleaching solution for several hours, for example, 3 to 10 hours, atroom or moderately Warm temperature and then to heat such goods for ashort period of time, preferably, 10 to 12 minutes, to about 100 C.with, for instance, a steam jet. Expediently the storage is effected ina tightly packed condition. This procedure is effective for bleach ingfibers, yarns, woven fabrics, knitted goods or other textile goods ofall types and especially those which are of cellulosic nature. The usualtextile bleaching agents, such as hydrogen peroxide, sodium peroxide,sodium perborate, sodium chlorite, peracetic acid and the like can beused in such procedure.

The object of the present invention is to provide a process in which thetime the bleaching agent acts on the goods could be shortenedsubstantially while at the same time attaining a higher degree ofwhiteness.

According to the invention it was unexpectedly found that the results ofa bleaching treatment with regard to the degree of whiteness, as well aswettability could be substantially improved while effecting a saving insteam Patented Aug. 13, 1968 and heat energy if, according to theinvention, the goods to be bleached are impregnated with the aqueousbleaching solution, such impregnated goods are stored at room ormoderately raised temperatures, for instance up to about 40 C. forseveral hours, for example, 3 to 10 hours, in a tightly packed state,and after such storage are treated in a pressure steamer at temperaturesbetween and 200 C. for 15 to 120 seconds. Preferably, suchpressuresteaming treatment is effected at temperatures between and 150 C. atcorresponding pressures for 30 to 60 seconds.

Peroxidic textile bleaching solutions, such as, for example, those ofhydrogen peroxide, sodium peroxide or sodium perborate, are especiallysuited for the process according to the invention. The process, forinstance,

can be carried out by impregnating the textile goods to be bleachedwith, for example, an alkaline hydrogen peroxide containing bleachingsolution, removing the excess solution to provideabout a 100% to 150%take up by the goods. Thereupon the goods are folded up or rolled up andleft to be acted on by the bleaching solution contained therein forseveral hours at room temperature. Thereafter, the goods are introducedinto a pressure steamer without repeating the impregnation or anintervening Wash and treated in such pressure steamer at thetemperatures indicated for a short time and then given the usual rinse.

While it is known that fabrics can be impregnated with an alkalineperoxide solution and then immediately treated at elevated temperaturesof at least C. for a short time with steam at corresponding pressures,such process only leads to a satisfactory white content if the goodshave been given an alkaline pretreatment.

With the process according to the invention the total time required forthe treatment of the goods to be bleached can be shortened substantiallywhile at the same time a higher degree of whiteness and a better removalof seed shells in theicase of cotton fabrics can be attained.Furthermore, the wettability of the goods bleached according to theinvention is considerably improved.

The results obtainable with the process according to the invention areillustrated in the following example in which it is compared with knownprocesses which do not include a pressure steam treatment.

Example The tests were carried out on desized Reutlinger nettle clothwhich still contained seed shells. The steaming apparatus employed wasan Obermaier HT apparatus. The nettle cloth was impregnated with anaqueous bleaching solution which per liter contained Water glass 38/40B. "ml-.. 30 NaOH g 10 H 0 (35% by weight) ml 40 Lamepon A (condensationproduct of oleic acid chloride and sodium lysalbinate) g 2 Wetting agent(lauryl sulfate) g 2 In all instances the cloth after impregnation wassqueezed out to a 100% bleaching solution content and then subjected tothe action of the retained bleaching solution at room temperature forthe periods indicated in the following table. The steam Was at atemperature of 130 C. which corresponds to a gauge pressure between 2.8to 3.2. After completion of the bleach the cloth samples were eachrinsed successively with hot, warm and cold tap water. The degree ofwhiteness, the time required for submerging when placed on water and thedegree of seed shell removal was determined for each bleached sample.The results are given in the following table:

impregnating such fibrous textile material with the aqueous peroxidicbleaching solution, removing the excess TABLE Room Pressure Degree ofTest- No. Temp. Steaming whiteness Submerging Time Seed Shell RemovalBleach (see) (percent) (hours) 18 77 Over 2 min. r Shell free.

3 60 80 o. 3 72 Still contained shells. 6 60 81. 9 2sec Shell free. fi73 90 sec Still contained shells. Starting material desized Over 10min..

As can be seen from such table, tests 2 and 3, which were according tothe invention, resulted in goods which were seed shell free, and hadgood wettability and a higher degree of whiteness than were obtained intests 1, 2a and 3a.

Analogous improved results were obtained when the above bleachingsolution was replaced by aqueous bleach- .ing solutions which per litercontained the ingredients given below.

Bleaching solution :1:

1. The process of bleaching fibrous textile materials with an aqueousperoxidic bleaching solution, the steps of bleaching solution, storingthe thus impregnated fibrous textile material for a period of about 3 to10 hours at a temperature between room temperature and moderately raisedtemperature, then subjecting the fibrous textile material to steam underpressure at a temperature between and 200 C. for a period of 15 to 120seconds.

2. The process of claim 1 in which the fibrous textile material containscellulosic fibers.

3. The process of claim 2 in which the steam treatment is carried out ata temperature between and C. for a period of 30 to 60 seconds.

References Cited FOREIGN PATENTS 539,280 4/1957 Canada. 577,546 6/1959Canada. 589,916 12/1959 Canada. 844,699 8/ 1960 Great Britain. 1,276,63510/1961 France.

LEON D. ROSDOL, Primary Examiner.

MAYER. WEINBLATT, Assistant Examiner.

